1. Field
This invention relates to an electronic device with an antenna for wireless communication, such as a portable computer.
2. Description of the Related Art
With remarkable progress in technology concerning an electronic device such as a portable computer in recent years, a wireless communication module such as wireless LAN or BLUETOOTH™ is mounted on some of such electronic devices.
A wireless LAN module features two antennas, namely a main antenna for performing transmission and reception and an auxiliary antenna for performing only reception. The structure with these two antennas contributes to improved radio reception quality, because the wireless LAN module switches between the main antenna and the auxiliary antenna according to a reception state, and maintains control of radio reception quality so as to maintain a more sensitive reception state. This is sometimes referred to as “spatial diversity reception”.
On the other hand, in the BLUETOOTH™ module, only one antenna for performing transmission and reception is provided. In addition, in the case where the wireless LAN module conforms to the IEEE 802.11b standard, the BLUETOOTH™ module and available frequency bandwidth overlap each other. When they are used at the same time, radio interference occurs, and each module may experience communication speed degradation.
From this point of view, in general, an antenna of the wireless LAN module and an antenna of the BLUETOOTH™ module are made independent of each other, and a total of 3 antennas are provided so as to suppress radio interference to a minimum. However, in a small sized electronic device such as a portable computer, downsizing and high density are required. Thus, there is tendency that an increasingly smaller space for mounting an antenna may be allocated in a cabinet.
For example, U.S. Pat. No. 6,560,443 discloses a multi-transceiver mobile terminal with two types of wireless communication modules that apply a technique of selectively switching one or two antennas by means of an antenna switching circuitry so as to share these modules. In this reference, the number of antennas mounted is reduced to two. However, this technique requires a control circuit for controlling the antenna switching circuitry to be switched according to the wireless communication state or the like of each of the wireless communication modules, and makes configuration complicated. In addition, one of two wireless communication modules is selectively used. In other words, only one wireless communication module can be connected to the antenna at a time, and the other module cannot be used at the same time.